package com.hmdp.service.impl;

import cn.hutool.core.lang.UUID;
import cn.hutool.core.util.BooleanUtil;
import com.hmdp.service.ILock;
import lombok.Builder;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;
import java.util.zip.DeflaterOutputStream;


@Slf4j
public class SimpleRedisLock implements ILock {

    private StringRedisTemplate stringRedisTemplate;
    private String name;
    private static final String KEY_PREFIX = "lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true)+"-";

    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;

    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    public SimpleRedisLock(String name,StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.name = name;
    }


    @Override
    public boolean tryLock(Long timeoutSec) {
        //获取线程id，作为key的value。
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        Boolean lock = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(lock);//防止返回时拆箱出现空指针异常。
    }

    @Override
    public void unlock() {
        //调用lua脚本，保证释放锁的原子性
        stringRedisTemplate.execute(UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX + name),ID_PREFIX + Thread.currentThread().getId());
    }

/*    @Override
    public void unlock() {
        //释放锁之前首先判断是不是自己的锁
        //获取线程标识
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        //获取锁中的标识
        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + threadId);
        //判断标识是否一致
        if(threadId.equals(id)) {
            stringRedisTemplate.delete(KEY_PREFIX + name);
        }
    }*/
}
